# CVE-2026-23221: bus: fsl-mc: fix use-after-free in driver_override_show()

> A race condition in the Linux kernel fsl-mc bus driver allows a use-after-free, potentially leading to code execution or system crash.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Feb 2026
- **Updated:** 11 May 2026
- **Also known as:** AZL-77930, BELL-CVE-2026-23221, DEBIAN-CVE-2026-23221, GHSA-jp99-8xc8-367m, ROOT-OS-DEBIAN-11-CVE-2026-23221, ROOT-OS-DEBIAN-12-CVE-2026-23221, ROOT-OS-DEBIAN-13-CVE-2026-23221, ROOT-OS-UBUNTU-2204-CVE-2026-23221, ROOT-OS-UBUNTU-2404-CVE-2026-23221, UBUNTU-CVE-2026-23221

## What is CVE-2026-23221?

CVE-2026-23221 is a high-severity use after free vulnerability in Linux kernel, published on 18 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

bus: fsl-mc: fix use-after-free in driver_override_show()

The driver_override_show() function reads the driver_override string
without holding the device_lock. However, driver_override_store() uses
driver_set_override(), which modifies and frees the string while holding
the device_lock.

This can result in a concurrent use-after-free if the string is freed
by the store function while being read by the show function.

Fix this by holding the device_lock around the read operation.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-23221?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23221?

Apply the vendor's patch.

## Is CVE-2026-23221 being exploited?

There is no known exploitation of CVE-2026-23221 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23221 and fix it if it is affected.

What it is: CVE-2026-23221 is a high-severity use after free vulnerability in Linux kernel, published on 18 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-23221 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-23221/ (Markdown: https://insights.sbomify.com/CVE-2026-23221/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23221
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23221
- OSV: https://osv.dev/vulnerability/CVE-2026-23221

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23221/
Summaries are generated and may contain mistakes; the official description above is the record.